1. Field
The present invention relates to signaling techniques between various platforms and, more particularly, to high speed signaling techniques for such communication.
2. Background Information
A variety of signaling protocols exist for communication via a bus or cable between a computer or host and a computer peripheral, for example. One such protocol or specification comprises the standard Universal Serial Bus (USB) specification, version 1.0, available from USB-IF, 2111 NE 25th. Ave. MS-JF2-51, Hillsboro Oreg. 97124. (hereinafter, xe2x80x9cUSB specificationxe2x80x9d). Although devices and other equipment that engage in signaling complying with the USB specification are gaining an increased presence in the marketplace, one disadvantage of this particular specification is that it is limited to operate at twelve (12) megabits per second (mb/s). Due to increasing microprocessor speeds, for example, a desire for high speed signaling relative to 12 mb/s, for example, is present and continues to gain momentum. It would be desirable if a technique existed in which relatively low speed signaling, such as 12 mb/s, for example, could be made compatible with a high speed signaling technique so that this high speed signaling is transparent to legacy devices performing low speed signaling.
Briefly, in accordance with one embodiment of the invention, a method of performing high speed signaling includes the following. A preamble signal and an end of packet (EOP) signal are transmitted at a low frequency using rail-to-rail voltage signal levels. Later, high frequency signaling is transmitted using a voltage signal level swing that is less than rail-to-rail.